The potential for using a free-growth system in the rehabilitation of poorly performing pole-stage broadleaf stands

Abstract

This paper is a literature review of the free-growth system, which may have potential for the rehabilitation of some poorly-performing pole-stage broadleaf stands. It involves releasing of a selected number of good quality stems from crown competition as a basis for the final crop. Generally, only stems with crowns adjacent to the potential final crop trees are removed. The aim is to increase diameter growth of the selected stems and thereby shorten the rotation length needed to achieve a given diameter. The treatment may result in a greater incidence of epicormic shoots, particularly in oak (Quercus spp.). To maintain stem quality, epicormics may need to be removed, which may make the free-growth system uneconomic. There is, however, some evidence to believe that this may not be the case. In addition, the free-growth system may also be applicable in species less prone to epicormics, such as ash (Fraxinus excelsior L.) and sycamore (Acer pseudoplatanus L.). The free-growth system may prove to be a useful system for the rehabilitation of poorly performing pole-stage broadleaf stands and, with the advent of Chalara ash dieback (caused by Hymenoscyphus pseudoalbidus V. Queloz et al.) in Ireland, may gain greater use for its ability to reduce rotation lengths.